The formulation of detergent compositions which effectively remove a wide variety of soils and stains from fabrics under wide-ranging use conditions remains a considerable challenge to the laundry detergent industry. Unsolved problems similarly exist for the formulator of automatic dishwashing detergent compositions (ADD's). These compositions are expected to efficiently cleanse and sanitize dishware, often under heavier soil loads. The problems associated with the formulation of truly effective cleaning and bleaching compositions for use by the consumer have been exacerbated by legislation which limits the use of effective ingredients such as phosphate builders in many regions of the world.
Most conventional cleaning compositions contain mixtures of detersive surfactants to remove a wide variety of soils and stains from surfaces. In addition, detersive enzymes, soil suspending agents, builders, brighteners, and the like may be added to boost overall cleaning. Many fully-formulated cleaning compositions contain oxygen bleach, especially as hydrogen peroxide, typical sources for which include perborate or percarbonate salts. While quite effective at high temperatures, high levels and high pH's, hydrogen peroxide loses much of its bleaching function at low to moderate temperatures, low to moderate perborate/percarbonate levels and/or low to moderate wash pH. Yet all of these are increasingly favored in consumer product use.
Various bleach activators such as tetraacetylethylenediamine (TAED) and nonanoyloxybenzenesulfonate (NOBS) have been developed to potentiate the bleaching action of perborate and percarbonate across a wide temperature range. NOBS is particularly effective on "dingy" fabrics.
A limitation with activators such as the widely commercialized TAED is that the wash solution or liquor should have a pH of about 10 or higher for best results. Since soils, especially from foods, are often acidic, detergent products are frequently quite alkaline or are buffered sufficiently to maintain a high pH so the bleach activator system can operate effectively throughout the wash. However, this need runs counter to providing milder formulations which could be improved in their compatibility with fabrics, glassware and/or skin. In cleaning operations below pH 10, on the other hand, many of the existing bleach activators lose their effectiveness or undergo competing side reactions which tend to produce ineffective byproducts.
The search, therefore, continues for more effective activator materials, especially for use in mildly alkaline washing liquors or with decreased levels of perborate or other sources of hydrogen peroxide. Improved activator materials should be safe, effective, and will preferably be designed to interact with troublesome soils and stains. Various activators have been described in the literature. Many are esoteric and expensive.
It has now been determined that certain selected bleach activators are unexpectedly effective in removing soils and stains from fabrics and hard surfaces such as dishes even under low alkaline wash conditions or with decreased levels of hydrogen peroxide source materials. The preferred activators also have advantageously high ratios of rates of perhydrolysis to hydrolysis and of perhydrolysis to diacylperoxide formation. Without being limited by theory, these unusual rate ratios lead to a number of significant benefits for the instant activators, including increased efficiency, avoidance of wasteful byproduct formation in the wash, increased color compatibility, increased enzyme compatibility, and better stability on storage.
When formulated as described herein, cleaning and/or bleaching compositions, including detergent compositions, are provided using the selected bleach activators to remove soils and stains not only from fabrics, but also from dishware in automatic dishwashing compositions, from kitchen and bathroom hard surfaces, and the like, with excellent results. Advantages of these embodiments include excellent performance at typical wash pH's, e.g., about 10, as well as unexpectedly superior performance at moderate wash pH, typically from about 7 to about 9. Also secured herein are novel activators designed to function well over a wide range of wash pH and hydrogen peroxide source levels. In short, the present cleaning/bleaching compositions and improved bleach activators, as further illustrated in the disclosure hereinafter, provide a substantial advance over those of the art.